Surface-effect transport support systems

ABSTRACT

A transport system comprising a surface-effect vehicle movable along a prepared track, the vehicle having means for defining a first fluid cushion of predetermined pressure below ambient pressure and cooperating with the track, and second means combining with the first means to define a second fluid cushion of a pressure lower than said predetermined pressure, so that the vehicle cooperates with track through superimposed fluid cushions.

O United States Patent 1 1 3,580,181

[72] Inventors J an H nri B rlin [50] Field of Search; 104/23 (R), Neuilly-sur-Seine; 23 (F8), 134 Francis Marie Jean Croix-Marie, Viry- Ch fin France [56] References CIted [21 Appl. No. 888,316 UNIT ED STATES PATENTS 1 PM Dec-29,1969 3,511,186 5/1970 Barthalon 104/23 1%] g :22: 3,515,073 6/1970 Faure 104/23 1 1 ssxgnee Plaisir mice Primary Examiner-Arthur L. La Point [32] Priority 1968 Assistant Examiner-D. W. Keen [33] France Attorney-Stevens, Davis, Miller & Mosher [31] 181,381

ABSTRACT: A transport system comprising a surface-efiect [54] EFFECT TRANSPORT SUPPORT vehicle movable along a prepared track, the vehicle having 28 Cl 15 D A means for defining a first fluid cushion of predetermined presrawmg sure below ambient pressure and cooperating with the track, [52] US Cl. 104/23FS, and second means combining with the first means to define a 104/ 134, 104/23 second fluid cushion of a pressure lower than said predeter- [51] Int. Cl. B60v 3/04, mined pressure, so that the vehicle cooperates with track B60v 1/06 through superimposed fluid cushions.

PATENTEDHAY25l9n- 3580.181

SHEET 1 OF 8 INVENTORS JEAN HENRI BERTIN F/G.:/ FRANCIS MARIE JEAN CROIX-MARIE WOQ M TORNEYS PATENTEU W25 I97! SHEET 2 0F 8 PATENIED W25 IHYI sum 3 or 8 PATENTED HAY25 I97! SHEET [1F 8 PATENTED W25 IHTI SHEET 5 [IF 8 SHEET 8 [IF 8 PATENTED HAYZS lsn SURFACE-EFFECT TRANSPORT SUPPORT SYSTEMS BACKGROUND OF THE INVENTION Transport and/or support systems are known comprising a vehicle associated with a prepared track, the vehicle being supported by at least one cushion of fluid under pressure, formed between the track and a wall which is subjected, on opposite sides, to the ambient pressure and to the lower pressure prevailing in the cushion of fluid, said lower pressure being hereinafter referred to as negative pressure.

The cushions of fluid under negative pressure in such systems are generally confined in chambers formed by confining walls, and the leakage gap between the ends of these walls and the surface of the track may be modified by irregularities in this surface, so causing the intake rate of the generator of fluid under negative pressure to vary.

OBJECT OF THE INVENTION An object of the invention is to provide apparatus for controlling the rate a which fluid enters the chambers, in order to improve the suspension of the vehicles in transport and/or support systems of the type described.

BRIEF SUMMARY OF THE INVENTION portion fixed in a fluidtight manner to the first means; and

means for keeping the first and second cushions of fluid under negative pressure, the pressure in the first cushion being greater than the pressure in the second.

FURTHER FEATURES OF THE INVENTION According to another feature of the invention, at least one first cushion of fluid under negative pressure is confined by a movable fitment substantially conforming to the shape of the track and cooperating with the latter by way of flexible confining walls, the second cushion of fluid being confined by at least part of the said fitment, the frame of the vehicle and at least one flexible sheet, this sheet enabling the movable fitment or at least a portion of this fitment to move relative to the vehicle frame, the said movable portion having low inertia due to its construction and advantageously forming, with the flexible confining walls, a very effective follower coupling.

According to a further feature of the invention, the negative pressures in the first and second fluid cushions are maintained by separate generators of fluid under negative pressure.

According to another feature of the invention, the negative pressure in a first fluid cushion is maintained by way of calibrated orifices formed in at least one wall of the movable fitment, enabling the first and second cushions of fluid under negative pressure to communicate with one another, the fluid therefore undergoing a pressure drop as it passes from the first to the second cushion, and the negative pressure in the second fluid cushion being maintained by a generator of fluid under negative pressure mounted on the vehicle.

In accordance with a still further feature of the invention, the area of contact between the frame or movable fitment and the flexible sheet defining the second cushion of fluid under negative pressure varies with the distance separating the frame from the fitment or from the movable portion of the fitment in a prescribed manner, which depends on the load carried by the vehicle; on the variation in the difference in pressure between the first and second fluid cushions, due to variations in the leakage gap between the ends of the walls confining the first fluid cushion and the track surface and the pressure drops between the fluid cushions; on the rigidity of the sheet; and on the positioning of the points at which the sheet is attached respectively to the movable fitment and the vehicle frame.

The characteristics of the vehicle suspension therefore depend essentially on the rate at which the pressure drops produced by the calibrated orifices vary with the rate of flow of the fluid under negative pressure, and on the rate at which the area of contact between the frame or chassis of the vehicle and the flexible sheet connecting the frame to the movable fitment varies with the distance separating the frame and chassis. Y

The various features of the invention and the manner in which they may be carried into practice will be clear from the following description with reference to the accompanying drawings, given by way of example only.

BRIEF DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 represents a section along a line 1-1 in FIG. 2, illustrating a first embodiment of a transport or support system according to the invention;

FIG. 2 shows a section along a line 11-" in FIG. I, on a smaller scale;

FIG. 3 shows a partial section on a line III-III in'FIG. 2;

FIG. 4 shows partial section through a second embodiment;

FIG. 5 shows a partial section through a third embodiment;

FIG. 6 shows a partial section along a line VIVI in FIG. 5, on a smaller scale;

FIG. 7 shows a partial section on a line VII-VII in FIG. 6;

FIG. 8 shows a partial section through a fourth embodiment;

FIG. 9 shows a partial section through the fourth embodiment, along the same plane as the section through the third embodiment shown in FIG. 7;

FIG. 10 is a partial section along a line X-X in FIG. 11, illustrating a fifth embodiment;

FIG. 11 shows a partial section along a line XI-XI in FIG. 10;

FIG. 12 shows a partial section through a sixth embodiment;

FIG. 13 shows a partial section along a line XIII-XIII in FIG. 14, illustrating a seventh embodiment; t

FIG. 14 shows a partial section along a line XIV-XIV in FIG. 13; and

FIG. 15 shows a section through another embodiment of a transport or support system according to the invention.

DESCRIPTION OF EMBODIMENTS FIGS. I and 2 illustrate a vehicle I adapted to form part of a transport or support system and to cooperate with a track 2,

whose cross section is in the form of an inverted T and which is supported by columns 3 situated at intervals along this track. The vehicle I has a portion la, which conforms to the shape of the track and bears apparatus for supporting the vehicle, and a cabin lb.

The apparatus for supporting the vehicle comprises:

a plurality of movable fitments 4, bearing flexible walls 5a, 5b confining a plurality of first cushions of fluid under negative pressure, between walls 4a, 4b and 4c of the fitments and surfaces 6a, 6b, 6c and 6d of the track 2;

two flexible sheets 7a, 7b, connecting each fitment in a fluidtight manner to the portion 1a of the vehicle frame, these sheets joining the frame substantially tangentially and joining each movable fitment substantially at right angles;

a second cushion of fluid under negative pressure, confined in a chamber defined by the plurality of movable fitments 4, the portion Ia of the vehicle frame, the flexible sheets 70, 7b, and casings 8a, 8b (FIG. 2) situated at the forward and rear ends of the vehicle;

a plurality of calibrated orifices I2, formed in the walls 40, 4b of each movable fitment and connecting the first and second cushions of fluid with one another;

ribs I7 reinforcing the portion Ia of the vehicle frame;

wheels 14 attached to the portion 1a and adapted to cooperatewith the surfaces 6a of the track and to support the vehicle when it is completely stationary or when the system for producing the fluid cushions is defective; and

shoes 15 attached to those portions of the vehicle opposite surfaces 16a, 16b of the track and operable by jacks (not shown), so that they can be applied like jaws to the surfaces l6a, 16b to brake the vehicle.

The second fluid cushion is maintained by appropriate means, for example a blower l0, situated at the end of a chamber 13 communicating with this fluid cushion by way ofa plurality of passages 11. The blower may be used both for maintaining the negative pressure in the second fluid cushion and for propelling the vehicle.

The first fluid cushions are connected to the same blower 10, which sucks the fluid into the said cushions through the calibrated orifices l2.

Each movable fitment 4 is connected in a fluidtight mannerto at least one another movable fitment by flexible walls 18 (FIG. 2). Similarly, each flexible sheet 7a or 7b bears, opposite the flexible walls 18, protuberances 19 enabling each fitment to move independently of the others (see below).

The casings 8a, 8b carry respective flexible walls 9a, 9b which cooperate with the track, minimizing the leakage between the flexible walls 5b and the track surface 6b so that the leakage between the walls 5a and the surface 6a always predominates.

As FIG. 3 shows, the casing 8a is formed of an envelope 20, whose cross section is identical in shape to that of the portion la of the vehicle frame; and an adjoining envelope 21 shaped in cross section like the flexible sheets 7a, 7b and the movable fitment 4, these two envelopes being rigidly connected to one another by a back 22 on which the flexible walls 9a, 9b are mounted. These walls may be advantageously made in two parts, so that they can be replaced when worn. The casings 8a, 8b are fixed to the frame portion la by screws (not shown).

The apparatus supporting the vehicle operates as follows:

Each movable fitment 4 is in a state of stable equilibrium,

'due partly to the difference between the pressures pl and p2 prevailing in the first and second fluid cushions respectively, the pressure p1 in the first cushion being greater than the pressure p2 in the second due to the pressure drops caused by passage of the fluid through the calibrated orifices l2, and partly to the tensions produced in the sheets 7a, 7b by the difference in the pressures prevailing on'each side of these sheets, these tensions being directed upwards and substantially vertically, whereas the pressure difference between pl and p2 produces a substantially vertical, downward force.

The vehicle is subject to the effect of the pressure difference between the second fluid cushion and the ambient medium. Since this pressure difference creates a force corresponding to the product of the pressure difference and the area defined by lines A and B, this force is directed upwards and balances the weight of the vehicle.

Any increase in the load on the vehicle reduces the distance separating-walls 23a belonging to the frame portion Ia from the walls 4c of the movable fitments 4. The flexible sheets 7a, 7b come into contact with the walls 23a, enlarging the area of contact between the sheets and the frame, and the area defined between the lines A and B becomes a larger area defined by lines A and B, so increasing the resultant of the pressures exerted on the vehicle.

Any reduction in the fluid leakage gap between the flexible walls 5a of a movable fitment and the track surfaces 6a, resulting, for example, from a fault in these surfaces, leads to a reduction in the rate of flow of fluid into the first cushion, a reduction in the pressures pl and p2 and a reduction in the pressure differentials at the orifices 12 related to the rate of flow, and therefore a reduction in the difference between the pressures pl and p2. A movable fitment which is no longer in a state of equilibrium will tend to move closer to the wall 23a due to the tension in the sheets 7a, 7b, restoring the leakage rate to its original level.

Any increase in the fluid leakage gap will have the opposite effect. I

If there is a local fault, each fitment, being movable independently of the other-fitments, will rise or fall (according to whether the fault is a projection or ahollow) as the fault passes the fitment. The period of oscillation of a movable fitment must be as short as possible to prevent transmission of the movement to the vehicle frame. Since the period depends not only on the sitting of the sheets 7a, 7b and on the pressure differentials across the caLibrated orifices 12, but also on the weight of the fitment, the fitment is a light structure, for exam ple in the form of metal sheeting reinforced with suitably arranged ribs or profiled portions. In the resulting system the confining walls follow the irregularities in the track, so limiting the wear on these walls and improving the suspension of the vehicle.

In the case of a fault extending over a large section of track, for example a step or an upward or downward gradient, each fitment rises or falls at the beginning of the fault and remains in this new position. The plurality of flexible sheets 7a, 7b come to bear on the walls 23a of the vehicle frame, communicating the movement carried out by the fitments progressively according to the variation in the areas defined by the lines such as A and B. It should be noted that, since the movable fitments 4 are connected together by the flexible walls 18, a fitment begins to move in the right direction before it reaches the fault which produces this movement, so that wear on the confining walls is further reduced.

FIG. 4 illustrates a second embodiment, in which the flexible sheets 70, 7b are arranged in the same way as in the first embodiment, but the two cushions of fluid under negative pressure associated with each movable fitment are produced by two separate appropriate means, for example two blowers 24, 25. The blower 24 maintains the negative pressure in the first fluid cushion by way of ducts 26, which are extended by a flexible duct 27 to avoid interference with the motion of the movable fitments 4. The blower 25 maintains the underpressure in at least one second fluid cushion by way of ducts 28. The two blowers may also be used for propelling the vehicle, as in the first embodiment, and are therefore advantageously situated on the median axis of the vehicle. They may be operated by two independent motor means or connected to a single motor means.

The apparatus for supporting the vehicle operates in the same way as in the first embodiment, with the difference that the pressure p2 in the second fluid cushion is substantially constant, only the pressure pl and therefore the difference between the pressures pl and p2 varying with the leakage gap between the walls 5a and surfaces 6a.

FIGS. 5 and 6 illustrate athird embodiment of apparatus for supporting a vehicle according to the invention. The movable fitment 4 is identical to that in the first embodiment, but the sheets 29a, 29b, analogous to the flexible sheets 7a, 7b in the first embodiment, are fixed in a fluidtight manner to the wall 4a of the movable fitment in a direction substantially perpendicular to this wall, and to a wall 23b of the portion 1a of the vehicle frame in a direction substantially tangential to this wall.

The first and second cushions of fluid under negative pressure associated with a movable fitment 4 are maintained by a single blower 10, the first fluid cushion being maintained by way of calibrated orifices 12 formed in the wall 4a of the fitment 4 between the two flexible sheets 7a, 7b. The pressure p1 in the first fluid cushion is therefore greater than the pressure p2 in the second fluid cushion. A movable fitment is subjected both to the effect of the pressure difference between the ambient medium and the pressure pl in the first fluid cushion, on the areas defined by the lines A and E, B and F,G and H, and I and J, and to the difference between the pressures p1 and p2 acting on the surface defined by the lines A and B. The points at which the sheets are attached, the sizes of these areas, and the number and diameters of the orifices 12 are so selected that the resultant of the pressures exerted on the movable fitment is upwardly directed, the fitment being in a state of stable equilibrium due to the action of this resultant and the tension in the sheets. 5 v

The vehicle is in a state of equilibrium because of the effect of the difference between the pressure of the ambient medium and the pressure p2 in the second fluid cushion on the surface defined by the lines C and D.

Operation is as follows. When the load increases, the vehicle frame tends to move away from the wall 40 of the movable fitment, and the sheets 29a, 2% move away from the surface 23b of the vehicle. Since the area defined by the lines C and D increases, the bearing force increases and restores the equilibrium.

If the leakage gap beneath the lips 5a is reduced by a fault in the track 2, the resultant of the pressures applied to the movable fitment increases, tending to lift the fitment, move the wall 5a away from the surface 6a, and restore the leakage rate to a level approximating to its original level, If, on the other hand, the leakage gap is increased, the resultant of the pressures is reduced and the fitment tends to drop due to the tension in the sheet. The wall 5a then moves closer to the surface 6a, restor- 7 ing the leakage rate to a level similar to its original level. The

movable fitments 4 are connected to one another by fluidtight flexible walls 30 (FIG. 6), in the same way as in the first em bodiment. At each end of the vehicle, a casing 31 carries a flexible wall 32, adapted to cooperate with the track and minimizing the leakage between the flexible walls 5b and the track surface 6b, so that the leakage between the walls 50 and surface 60 always predominates.

As FIG. 7 shows, the casing 31 is formed of an envelope 33a having the same cross section as the portion 1a of the vehicle frame and connected to an envelope 33b which has the same cross section as the flexible sheets 29a, 29b and the movable fitment 4 shown in FIG. 5. These two envelopes are rigidly connected by a back 35 (FIG. 6), which carries the flexible wall 32. A rib 34 reinforces this assembly. The casing 31 is fixed to the frame portion 1a by screws (not shown).

FIG. 8 illustrates a fourth embodiment of apparatus for supporting a vehicle according to the invention. The movable fitment 4 is identical to a fitment in the first embodiment, but the flexible sheets 37a, 37b, which are equivalent to the flexible sheets 29a and 29b in the third embodiment, are fixed in a fluidtight manner to the wall 4a of the movable fitment in a direction substantially tangential to this wall, and to the wall 23b of the frame portion la in a direction substantially per pendicular to this wall.

This apparatus operates in the same way as that shown in FIG. 5, but the stress due to the resultant of the pressures applied to the movable fitment 4 is exerted on the vehicle frame at the level of the lines A and B. The sheets 37a, 37b, which must transmit a large proportion of this stress, are advantageously reinforced by stiffening ribs 38a, 38b, in such a way that the sheets remain curved to some extent. When the load on the vehicle increases, the sheets 37a, 3 7b move away from the movable fitment and the area defined by the lines A and B increases, so increasing the vehicle bearing force, some of which is transmitted by the sheets 37a, 3712.

At each end of the vehicle, a casing 39 (FIG. 9) fulfills the same role as the casing 31 shown in FIG. 7. Its envelope 40, however, conforms to the cross section of the sheets 37a, 37b.

FIGS. 10 and 11 illustrate a fifth embodiment of apparatus for supporting a vehicle according to the invention, in which the movable fitments 4 also serve to support the vehicle when the latter is stationary. The fitments must therefore be strong enough to support the weight of the vehicle, while at the same time, for the same reasons as in the preceding embodiments, being as light as possible. To this end, each movable fitment is formed by an assembly of metal beams 40, for example T- beams or angle irons, interconnected by brackets 41 and covered by plates 42 of rigid sheet iron or sheet steel for greater rigidity.

The first cushion of fluid under negative pressure associated with a movable fitment 4 is confined by an envelope 46 and lips 5a, 5b. The envelope 46 is rigidly connected to the structure of the movable'fitment by a wall 47 containing calibrated orifices 12, which connect the first cushion of fluid under negative pressure to the second cushion of fluid under negative pressure, which is confined between the walls 47 and 48 and the flexible sheets 44a, 44b. The walls 47, 48 are interconnected by a lattice beam 49, which absorbs the effects of tension in the sheets and the force produced by the difference between the pressures pl and p2 in the two fluid cushions. Flexible walls 54 provide fluidtight connections between the movable fitments 4 (FIG. 11).

Each movable fitment 4 has two wheels 52, mounted on pivots 52a adapted to cooperate with the surfaces 6a of the track 2 when the vehicle is at a standstill. Each fitment, when supported in this way, supports the vehicle frame by way of struts 43 which cooperate with surfaces 45a, 45b on the vehicle, so' that the flexible sheets 44a, 44b need not bear the weight of the vehicle. These sheets 44a, 4412 are fixed respec-.

tively, in a fluidtight manner, to surfaces 51a, 51b on the vehicle frame in direction substantially tangential to these surfaces, and to the wall 48 of the movable fitment in a direction substantially perpendicular to this wall.

At each end of the vehicle, a plate 55 (FIG. 11) is attached to the beams 40 and walls 47, 48 in a fluidtight manner, to confine the second cushion of fluid under negative pressure. A flexible sheet 56 connects the flexible sheets 44a, 44b to one another, also in a fluidtight manner. A lip 57 attached to the plate 55 cooperates with the track 2.

FIG. 12 illustrates a sixth embodiment of apparatus for supporting the vehicle according to the invention, identical in design to that shown in FIG. 10 except as regards the at- I tachment of the flexible sheets 50a, 50b. The latter are attached to the surfaces 51a, 51b of the vehicle frame in a direction substantially perpendicular to these surfaces, and to the wall 48 of the movable fitment in a substantially tangential direction.

This apparatus operates in the same way as that illustrated in FIG. 6, and, for the same reasons, the flexible sheets 50a, 50b, are reinforced with ribs 53a, 53b.

FIGS. 13 and 14 illustrate a further embodiment of apparatus for supporting the vehicle according to the invention, in which only plates 59 hearing the confining walls 5a are mobile. A fitment 60 is rigidly connected to the frame portion 1a by ribs 61 and is connected in a fluidtight manner to a plate 59 by a flexible wall 62. The plates 59 hinge on pivots 63 mounted on bearings 64.

The first cushion of fluid under negative pressure opposite each plate 59 is confined in a chamber defined by the fitment 60, the plate 59, the flexible wall 62 and the confining walls 5a, 5b. The second fluid cushion is confined in a chamber defined by the fitment 60, the frame portion In and flexible sheets 65a, 65b which provide a fluidtight connection between one end of each plate 59 and the surface 230 of the vehicle frame. The flexible sheets 65a, 65b arranged in the same way as in the first embodiment.

The first and second cushions of fluid under negative pressure intercommunicate through calibrated orifices 66 and are maintained by a single blower 70.

Any one plate 59 is in a state of stable equilibrium due t the effects of the difference between the pressures p1 and p2 in the first and second fluid cushions on each side of this plate, of the tension in the sheet and of the supporting reaction associated with the hinging pivot 63. Since the area defined by the lines A and B is greater than that defined by the lines A and C, and the pressure pl in the first fluid cushion is greater than the pressure p2 in the second, the resultant of the pressures exerted on the plate 59 produces a torque in the direction of an arrow F about the hinging pivot 63, the resultant being balanced by the tension in the sheet 65a. The same applies to the plate 59 attached to the sheet 65b.

Any increase in the load on the vehicle reduces the leakage gap between the flexible walls 5a and the track surfaces 6a, causing a reduction in the difference between the pressures p1 and p2 and therefore a reduction in the torque exerted on the plates 59. Due to the tension in the sheet, the plates 59 move about their pivots 63 in the direction of the arrow F1, restoring the leakage rate to a level similar to its original level. Since the sheets 65a, 65b then come to bear on the surfaces 23a, 23b, the lift of the vehicle is increased.

The same phenomenon occurs if a fault in the track reduces the leakage gap beneath the flexible walls 5a. The reverse occurs if the leakage gap is increased. Shock absorbers 66 are provided between the walls 23aand plates 59, to prevent the latter from vibrating due to repeated stressing.

The flexible walls 5a, 5b are connected together in a fluidtight manner by flexible sheets 67, ensuring continuity of the chamber in which the first cushion of fluid under negative pressure is confined. A flexible wall 75 provides a fluidtight connection between each sheet 59 and another sheet 59, ensuring continuity of the chamber confining the second cushion of fluid under negative pressure and enabling each plate 59 to rotate independently of the other plates.

Similarly, a casing 68 isattached to each end of the vehicle and carried a flexible wall 65 adapted to cooperate with the track 2, to prevent any leakage at the track surfaces 6b, 686, and 6d.

FIG. illustrates a vehicle 1 embodying the invention, cooperating with a track 71 having a cross section in the form of an inverted T with two extensions 72a, 72b, which also have keep the two cushions of fluid under ne ative pressure.

5. A system as claimed in claim 1, w erem the first means comprise at least one rigid wall spaced relative to the track, and at least one flexible wall attached in a fluidtight manner to the rigid wall and extending towards the track as far as the vicinity of the track. 7

6. A system as claimed in claim 5, wherein the second means comprise at least part of the frame of the vehicle and at least one of the rigid walls forming part of the first means.

8. A system as claimed in claim 1, further comprising connecting means connecting the first cushion of fluid under negative pressure to the third means.

9. A system as claimed in claim 8, wherein the said connecting means comprise at least one flexible connecting means attached in a fluidtight manner to the first and second means.

10. A system as claimed in claim 1, wherein the second means are disposed around the first means.

11. A system as claimed in claim 1, wherein the second means are placed beside the first means.

12. A system as claimed in. claim 1, wherein the first means are made from light material, whereby the first means have low inertias.

cross sections in the form of an inverted T and which are arranged symmetrically and substantially at right angles to the plane of symmetry of the track. The vehicle has support apparatus 74 identical to that described in the first embodiment (FIG. 1). Similarly, support apparatuses 73a, 73b identical to the apparatus 74 cooperate with the extensions 72a, 72b to ensure guiding of the vehicle.

When the vehicle is subjected to a lateral force in the direction of the arrow F, due, for example, to centrifugal force exerted on the vehicle on a bend or to the effect of wind on the vehicle, the apparatuses 73a, 73b,- operating in the same way as the apparatus described above, restore the transverse equilibrium of the vehicle. The same applies if a force is applied in the opposite direction from the arrow F.

Each apparatus 73a, 73b and 74 maintains two cushions of fluid under negative pressure, by means of separate blowers 76a, 76b, 77 respectively,

Obviously, the cushions of fluid under negative pressure in each apparatus might be maintained by a single blower drawing fluid into appropriate ducts connecting these apparatuses.

It should be noted that any of the embodiments of apparatus described above may be applied to this type of vehicle.

We claim:

1. A transport or support system, comprising a track and a surface-effect vehicle movable along the track and comprising:

a frame; Y

first means adapted to cooperate with the track to confine a first cushion of fluid under negative pressure;

second means adapted to cooperate with at least part of the first means to confine at least one second cushion of fluid under negative pressure, these second means comprising at least one flexible portion fixed in a fluidtight manner to the first means;

third means for keeping the first cushion of fluid under negative pressure at a given nominal pressure; and

fourth means for keeping the second cushion of fluid under negative pressure at a pressure lower than the said nominal pressure.

2. A system as claimed in claim 1, further comprising means for producing a flow of fluid between the first and second cushions of fluid under negative pressure.

3. A system as claimed in claim 2, wherein the means for producing a flow of fluid between the first and second cushions of fluid under negative pressure comprise means for creating a pressure drop between these cushions.

4. A system as claimed in claim 3, wherein the same means 13. A system as claimed in claim 1, wherein the first means are adapted to support the weight of the vehicle. g

7. A system asclaimed in claim6, wherein the said part of the frame of the vehicle is adapted to support the weight of the vehicle.

14. A system as claimed in claim 1, wherein the first means comprise meansfor connecting the first means rigidly to the frame ofthe vehicle.

15. A system as claimed in claim 1, wherein the said portion comprises a flexible strip.

16. A system as claimed in claim 1, wherein the said flexible portion is connected substantially tangentially to the second means.

flexible 17. A system as claimed in'claim 1, wherein the said flexible portion is connected substantially at right angles to the second means.

18. A system as claimed in claim 1, wherein the said flexible portion is connected substantially tangentially to the first means. 7

19. A system as claimed in claim 1, wherein the said flexible portion is connected substantially at right angles to the first means.

20. A system as claimed in claim 1, wherein the first means comprise at least one portion which is fixed relative to the vehicle and at least one portion which is movable relative to the fixed portion.

21. A system as claimed in claim 20, further comprising rib means rigidly connecting the fixed portion to the second means.

22. A system as claimed in claim 20, further comprising articulating means adapted to support the movable portion.

23. A system as claimed in claim 20, wherein the movable portion comprises at least one flexible wall connected in a fluidtight manner to the movable portion and extending towards the track as far as the vicinity of the track.

24. A system as claimed in claim 20, further comprising shock-absorbing means associated with the movable portion.

25. A system as claimed in claim 1, wherein the second means comprise elements adapted to cooperate with the track in order to support the vehicle when stationary.

26. A system as claimed in claim 1, wherein the first means comprise elements adapted to cooperate with the track in order to support the vehicle when stationary.

27. A system as claimed in claim 1, wherein the cross section of the track is in the form of an inverted T.

28. A system as claimed in claim 1, wherein the cross section of the track is in the form of an inverted T with two guiding extensions, each in the form of an inverted T, arranged symmetrically and substantially at right-angles to the longitudinal plane of symmetry of the track. 

1. A transport or support system, comprising a track and a surface-effect vehicle movable along the track and comprising: a frame; first means adapted to cooperate with the track to confine a first cushion of fluid under negative pressure; second means adapted to cooperate with at least part of the first means to confine at least one second cushion of fluid under negative pressure, these second means comprising at least one flexible portion fixed in a fluidtight manner to the first means; third means for keeping the first cushion of fluid under negative pressure at a given nominal pressure; and fourth means for keeping the second cushion of fluid under negative pressure at a pressure lower than the said nominal pressure.
 2. A system as claimed in claim 1, further comprising means for producing a flow of fluid between the first and second cushions of fluid under negative pressure.
 3. A system as claimed in claim 2, wherein the means for producing a flow of fluid between the first and second cushions of fluid under negative pressure comprise means for creating a pressure drop between these cushions.
 4. A system as claimed in claim 3, wherein the same means keep the two cushions of fluid under negative pressure.
 5. A system as claimed in claim 1, wherein the first means comprise at least one rigid wall spaced relative to the track, and at least one flexible wall attached in a fluidtight manner to the rigid wall and extending towards the track as far as the vicinity of the track.
 6. A system as claimed in claim 5, wherein the second means comprise at least part of the frame of the vehicle and at least one of the rigid walls forming part of the first means.
 7. A system as claimed in claim 6, wherein the said paRt of the frame of the vehicle is adapted to support the weight of the vehicle.
 8. A system as claimed in claim 1, further comprising connecting means connecting the first cushion of fluid under negative pressure to the third means.
 9. A system as claimed in claim 8, wherein the said connecting means comprise at least one flexible connecting means attached in a fluidtight manner to the first and second means.
 10. A system as claimed in claim 1, wherein the second means are disposed around the first means.
 11. A system as claimed in claim 1, wherein the second means are placed beside the first means.
 12. A system as claimed in claim 1, wherein the first means are made from light material, whereby the first means have low inertias.
 13. A system as claimed in claim 1, wherein the first means are adapted to support the weight of the vehicle.
 14. A system as claimed in claim 1, wherein the first means comprise means for connecting the first means rigidly to the frame of the vehicle.
 15. A system as claimed in claim 1, wherein the said flexible portion comprises a flexible strip.
 16. A system as claimed in claim 1, wherein the said flexible portion is connected substantially tangentially to the second means.
 17. A system as claimed in claim 1, wherein the said flexible portion is connected substantially at right angles to the second means.
 18. A system as claimed in claim 1, wherein the said flexible portion is connected substantially tangentially to the first means.
 19. A system as claimed in claim 1, wherein the said flexible portion is connected substantially at right angles to the first means.
 20. A system as claimed in claim 1, wherein the first means comprise at least one portion which is fixed relative to the vehicle and at least one portion which is movable relative to the fixed portion.
 20. A system as claimed in claim 1, wherein the cross section of the track is in the form of an inverted T with two guiding extensions, each in the form of an inverted T, arranged symmetrically and substantially at right-angles to the longitudinal plane of symmetry of the track.
 21. A system as claimed in claim 20, further comprising rib means rigidly connecting the fixed portion to the second means.
 22. A system as claimed in claim 20, further comprising articulating means adapted to support the movable portion.
 23. A system as claimed in claim 20, wherein the movable portion comprises at least one flexible wall connected in a fluidtight manner to the movable portion and extending towards the track as far as the vicinity of the track.
 24. A system as claimed in claim 20, further comprising shock-absorbing means associated with the movable portion.
 25. A system as claimed in claim 1, wherein the second means comprise elements adapted to cooperate with the track in order to support the vehicle when stationary.
 26. A system as claimed in claim 1, wherein the first means comprise elements adapted to cooperate with the track in order to support the vehicle when stationary.
 27. A system as claimed in claim 1, wherein the cross section of the track is in the form of an inverted T. 